The Risk Factor of Malignancy in ACR BI-RADS 4 Mammography Lesion Which was Invisible in Breast Ultrasound

The ACR-BI-RADS is commonly used to assess breast lesion during breast cancer screening by mammography as recommended by the American College of Radiology. From October 2006 through October 2008, our group have identified 27 cases of breast lesion by mammographic screening. Although all these cases were reported as ACR-BI-RADS 4. Yet breast ultrasound revealed negative results. Among theses 27 cases, 26 had received wired localization of the lesion under mammography and surgery to remove the lesion. One patient selected breast MRI and was reported as ACR BI-RADS 2. For patients who had surgery, only seven patients were identified as malignancy (six ductal carcinoma in situ and one infiltrating ductal carcinoma). The rest 19 patients were reported as benign lesion. The aim of this study is therefore to identify the risk factor of malignancy based on the variables gathered from these patients so that the unnecessary breast biopsy can be obviated in the future. Fisher exact test for testing the difference rate between the benign and the malignancy groups on these variables including menopause (pre-or post) status, breast feeding, hormone replacement, family history of breast cancer, number of child birth, age of first child birth, age of menarche. Out of these variables, we found that only post-menopause status was significant linked to the occurrence of malignancy and hence to be a genuine risk factor for malignancy.